promote: Delete unused functions.

promotion_key, fuzz_impressions, campaign_lock, complimentary.
PromotionWeights.get_campaigns can filter by link and sr_names.
make_daily_promotions: delete test mode.
Stop using LiveAdWeights.
Delete LiveAdWeights.
Cleanup house ads query.
Don't worry about everything failing in promote.
promote: cleanup.

Consolidate duplicated logic and make methods more direct. There were
many monolithic methods that did many things and were called all over
the place when the desired action was just one piece of the method.
make_daily_promotions only runs for current time.

Specifying an offset would cause the wrong campaigns to go live.
Basic support for house priority campaigns.
promote.py: remove unused imports.
promote.py: Delete unneeded wrap_promoted and sponsor_wrapper.
Update all_live_promo_srnames when needed.
PromoCampaign: add default value for trans_id.
authorize: Add exception handling to is_charged_transaction.
Show recommended content in /explore

Shows a mix of content from:
- subreddits recommended for the user (based on subscriptions and multis)
- rising threads
- items from discovery-focused subreddits

Listing items emphasize the subreddit name and have feedback controls.

The AccountSRPrefs class builds a user preferences model on-the-fly from
subscriptions, multireddits, and a record of recent user feedback.

The AccountSRFeedback column family stores a user's recent interactions with
the recommendation UI. For example, it records which srs the user dismissed
as uninteresting, and keeps track of which srs were recommended recently to
make sure we don't show the same ones too often.

Each type of feedback has a ttl after which it disappears from the db.
Remove sr_discovery from example.ini

Internal promotions can now be run as house ads, so this variable is no
longer needed.
Not all dialects are in need of translators

This change causes language dialects to not be
marked with a (*) on the prefs page if the base,
generic language is sufficiently translated.
all_live_promo_srnames: Eliminate memoize expiration time.
Use hadoop version 1.0.3.